Sunday, November 16, 2014

The curse of averages

The curse of clear and simple graphics is that they often make you wonder if the stories they tell aren't much more complicated, nuanced, and messy than they seem.

At this same moment I'm enjoying the Sunday edition of The New York Times and a large cup of coffee. I've just stopped on a piece that describes the woes of LaGuardia Community College to raise money from private donors. LaGuardia CC serves tens of thousands of students from lower-middle class and poor families. The largest gift it has ever received was just $100,000. Compare that to the gift that Steve Ballmer is giving Harvard to hire just 12 Computer Science professors and you'll get an idea of the huge imbalances that exist in the U.S. higher education system.

That's the message that the striking chart on the left depicts. It's impressive, isn't it? And still, it made me think for a few minutes that this could be a great exercise for future visualization classes: Go to the National Center for Education Statistics, the source the Times used. Download the data. Then, don't just visualize averages. They are the equivalent of a good headline so, sure, they must be the first thing to show, but they may not be enough to be accurate and truthful. Show ranges and variation from the mean or median, too. Design histograms. Explore the data at the state or regional level. Perhaps an analysis of higher granularity and detail will yield even more interesting insights.